
Following in the tradition of other Magic blocks, Ravnica takes place in a plane of the multiverse that was previously unexplored in the game's backstory. The world of Ravnica is an ecumenopolis, a vast city that covers the entire surface of its planet, and is home to a diverse assortment of sentient races. Much power in Ravnica is held by the ten "guilds", political factions that each represent a combination of two of Magic 's five colors. The mythology of Ravnica is loosely derived from Slavic folklore, and the character names reflect this. This plane was revisited in the Return to Ravnica block, and the Guilds of Ravnica, Ravnica Allegiance and War of the Spark sets. Ravnica was conceived following the success of Invasion. Invasion, released in 2000, emphasized interactions between the colors, and it was one of Magic's most popular releases. Magic's lead designer, Mark Rosewater, wanted to expand on the multicolor theme in a new way. Therefore, the design of Ravnica is based around ten two-color pairs, including cards in which those pairs of colors work in concert. The Ravnica cycle is functionally different from the Invasion cycle due to how the multicolored or multicolor-themed cards are distributed among the three sets that make up each cycle. In the Invasion cycle, for example, the first two sets ( Invasion and Planeshift) centered around friendly color pairs in each of the five featured combinations of three colors (Nightscape/Crosis, Stormscape/Dromar, Sunscape/Treva, Thornscape/Rith, and Thunderscape/Darigaaz), two of them would be enemies of each other but both would be allies of a third central color (example: in a card like Ancient Spring that focuses on the white/blue/black combination, white and black are enemies of each other but both are allies of blue).

The last set, Apocalypse, emphasized enemy color pairs in each of the five featured combinations of three colors ("Ana", "Ceta", "Dega", "Necra", and "Raka"), two of them would be allies of each other but both would be enemies of the third (example: for Urborg Elf, blue and black are allies of each other but enemies of green).

However, the color combinations that are featured in each set of the Ravnica cycle are determined by which guilds are important in that stage of the story. All the multicolor cards in the Ravnica cycle (and many other cards) are associated with one of the ten guilds.

Ravnica emphasized Boros, Dimir, Golgari, and Selesnya Guildpact emphasized Gruul, Izzet, and Orzhov and Dissension emphasized Azorius, Rakdos, and Simic. Each symbol is a circle halved diagonally, in which the top left half is one color and the bottom right half another. A smaller version of the color's icon (sun for white, skull for black, etc.) appears in the corresponding half.
